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`@uiten taies stent titre.

GEORGE C. HOWARD, OF PHILADELPHIA. PENNSYLVANIA.

' Letters Pavan No. 61,738, dated February s, 1867.

IMPROVEMETS IN DRESSING GRINDSTONES TO ALL WHOM IT MAY CON CERN:

Be it known that I, GEORGE C. HOWARD, of Philadelphia, in the county ofPhiladelphia, in the State of Penn- Sylvania, have invented certain newand useful Improvements on Machines for Dressing Grrindstones; and I dohereby declare that the following is a full, clear, and' enactdescription of the construction and operation of the same, referencebeing had to the annexed drawings, making a part of this specification,in which- Figure 1 is a View of grindstone and box, with machineattached.

Figures 3 and 2 are perspective views of-the two parts which form thecase for the cut terwheel; anu

Figure 4 isan end view of the cutter-wheel case and post.

The nature of my invention consists in an improved method in traversingand adjusting the machine, and 'makingits details in such a shape thatthe sand, dust, and grit are effectually prevented from entering theworking parts of the apparatus.A

To enable others skilled in the art to make and use my invention, I willproceed to describe its construction and operation.

The cutter-wheels A, which fit tight on the journal b-I, fig. 1, and 6,iig. 4, (dotted) are placed in a case, c, which allows only so much ofthe cutters to protrude as is necessary to bring them in contact withthe stone, and prevents the grit and sand 'from entering the journals.The traverse sliding surfaces are protected from dirt by the U-shapedprojection onthe case c, by the plate d, or other suitable means.Diierent methods for traversing the cutter-Wheels across the face of thestone have to be adopted to snit the various' shapes of' grindstoneboxes and diierent forms of the face cf sto.nes. V

1. Fig. 1 'is a machine fordressing straigh faces. Its details are asfollows: e is a base-plate', which has posts ff, on'which the case c istraversed by means of the crank g and screw L, (dotteih) which worksthrough a nut in one of the posts f, or by therack z' and pinion j, orother suitable devices. As the stone wears down, the machine is eitherdrawn toward it by the screw 7c, which passes loosely through the clampZand screws into the base-plate e, or it may be pushed forward by theset-screws r r. After it has been set in contact with the stone, it isfastened securelyto the box y by the bolt z. The case c has holes m(iig. 2) bored in it, to receive the .journals of the cutter-wheels, andis made in two sections (figs. 2 and 3)w fastened together by boltspassing through the holes n n n. Should the stone happen torun in thedirection of the arrow, iig. 4, it would lift the case from the postsff.'V To prevent this, projections o o (figs. 2, 3, and 4) are made onthe case c, which hea-x* against corresponding projections on the postsThe projections o o, however, do not extend thefull length ofthe case,but spacespp, corresponding infwidth tothe posts ff, are left in. suchavmanner that when both sections (figs. 2 and 3) are bolted together thedistance between the space in iig. 2 and the spacepin g. will be equalto the distance between the posts ff, so that the case e may be droppedon; the screw z. will then enter the nut in that post, which has enteredthrough the space nearest tol the cutter=wheels, (tig. 3 g) byturns ingthe screw the case slides on the posts ff and the projections a o moveLinder the corresponding projections on the posts ff. (The centre of thecutting-wheels and the centre of the traversing screw are not inthe sameline, as shown in iig. 4, by which we are ena-bled to make the bearingsfor the cutting-wheel journals as long as desired without taking up anyspace inside the traversing slide.) VWhere economy in space isdesirable, ears or bosses s s are made on the case e, (fig. 4,) slidingin or on. guides, which latter are stationary, so that the dressingapparatus canbe traversed across the faceioi the stone without everhaving any of its parts projecting over the side of the grindstone box.

2. Fig. l shows the arrangements for dressing cnrved-faced grindstones'.g is the case, which V'encloses'the cutter-wheel; it slides in dove-tailgrooves upon thc curved rest d, which moves around an imaginary or Vrealcentre, or slides in annular grooves, to suit the desired convexity orconcat-ity oil-the stone. The rest d is traversed usually by a toothedsector and pinion, similar to the rack i and pinion j on machine I, iig.1; but a worm-wheel and tangent-screws may be advantageously substitutedin some cases. Either the U-slide form, the slide-restform, (both shownin fig. 1,)'or the form in which the case c slides by its ears or bosseson uides as described above, ma I be used for dressinfy curved-facedcrindstones. The )ieee 10. on the o f g 1 D D l f P 0 a v `fig. I, is arest for grinding tools.

The operation of the machine is as follows: When the stone has wornirregular, the apparatus is set forward, by the means described, untilit is in contactwith the stone; then it is traversed across the face, asabove explained, and a regular, perfectly circular stone will 'be theresult. Instead of traversing the apparatus by hand, .a pulley may beput in place of the crank g, and connected with another pulley on theshaft u by a belt, so that by means of any one of the many devices forobtaining a'rectilinear reciprocating motion the case can be traversedautomatically across the face of the stone.

I claim as my invention7 and desire to secure by Letters Patent Thecombination of long bearings for cutting-wheel b, the rests F, the lipo, and ears s, as set forth and for the purposes described.

GEO. C. HOWARD.

Witnesses:

SAML. B. HOWARD, G. W. EDWARDS.

